Sorting methods and machines have been known and practiced for many years in the production of goods including comestible articles. The machines found in the art include types that utilize reflecting electromagnetic radiation in the form of light to determine the optical reflective characteristics of the articles in the product stream using color as a determinant followed by an ejector to successfully remove offending articles. A notable example of such a sorter is the High Speed Mass Flow Sorting Apparatus for Optical Inspection and Sorting Bulk Food Products as shown in U.S. Pat. No. 5,887,073, and which is assigned to Key Technology, Inc.
Successful removal of offending or undesirable articles has been practiced to varying degrees of efficiency using several different approaches including air ejection and mechanical diversion. Experience has shown that air ejection techniques are suitable for a wide range of article types, but is best applied for smaller, less dense articles that can be easily influenced by a jet of fluid. Examples of articles suitable for air ejection include peas, corn, potato strips, potato crisps, and foreign material. Air ejection as commonly practiced utilizes a plurality of electrically controlled valves that are individually controlled by a machine vision system, and targeted toward offending or undesirable articles in a product stream. Thus, the undesirable articles are dislodged from their course of travel and caused to take an alternate path, removing them from the product stream.
Alternatively, mechanical diversion is similarly suitable for a wide range of articles, however, it is best applied for larger articles that are less susceptible to the physical influence caused by a jet of fluid. Examples of articles suitable for mechanical diversion include oranges, grape fruit, onions, and potatoes. Mechanical diverters are known in the art to require more frequent maintenance than air ejectors. In addition, mechanical diverters are more prone to undesirably bruised articles during a diversion.
An example of a sorter using a mechanical diversion arrangement is found in U.S. Pat. No. 5,979,667, where a rigid paddle is taught, and which selectively strikes articles from the product stream thereby forcing them into another path of travel. In this reference, a pulsed light sensor receives reflected light from a product stream of articles such as tomatoes. A color comparator utilizes information supplied from the pulsed light sensor to identify undesirable articles in the product stream. A pneumatically operated, and electrically controlled paddle is positioned so that undesirable articles are expelled from the product stream by striking them during their movement along a path of travel to send them to an alternate location. This reference also teaches the option of reversing the logic so that the moveable paddle is used to divert acceptable articles. Unfortunately, the striking action of the paddle upon the article during its course of travel has the potential to bruise the articles, thereby reducing their perceived value.
Another example of relevant art is found in U.S. Pat. No. 5,509,537 where a flexible finger is used to selectively strike undesirable articles from the product stream. Here, the flexible finger is presented as an alternative to the paddle described, above. One might expect that the striking flexible finger might decrease any adverse effects caused by the impacts made to the articles traveling in the product stream. However, it would appear that a flexible finger would also decrease the accuracy of the ejection operation by nature of its flexibility.
The present invention overcomes this and other limitation of the prior art. For instance, none of the aforementioned teachings, or other examples in the art disclose a sorter that utilizes a mechanical diverter having a concave shape that can gently redirect undesirable articles to another path of travel for further processing. In addition, the art does not teach the combination of utilizing both an air ejection device, and mechanical diversion in a single sorter arrangement.